Both ovarian fluid and female urine increase sex steroid hormone levels inmature Atlantic salmon (Salmo salar) male parr

We compared the ability of urine and ovarian fluid from female Atlantic sal mon (Salmo salar) to stimulate increase in plasma concentrations of sex ste roid hormones in mature conspecific male parr (priming effect of the stimul i). We also tested the hypothesis that prostaglandin F-2 alpha (PGF(2 alpha )) may act as a priming pheromone in the tested stimulants. Individual male s of salmon parr were exposed to female urine, ovarian fluid, urine-ovarian fluid mix, or PGF(2 alpha) Plasma concentrations of the sex steroids of 17 ,20 beta -dihydroxy-4-pregnen-3-one (17,20 beta -P) were higher in males ex posed to urine, ovarian fluids, and PGF(2 alpha), compared to control males . PGF(2 alpha). and a mixture of urine and ovarian fluid also gave increase d concentrations of 11-ketotestosterone (11-KT). Concentrations of PGF(2 al pha) were higher in ovarian fluids than in urine. A behavior test with matu re male part in a fluviarium showed neither attraction to nor avoidance of 0.1 nM PGF(2 alpha), but plasma levels of 17,20 beta -P were significantly higher in exposed males compared to controls.